#include <gtest/gtest.h>
#include <XCEngine/Resources/Mesh/MeshLoader.h>
#include <XCEngine/Resources/Mesh/MeshImportSettings.h>
#include <XCEngine/Core/Asset/ResourceTypes.h>
#include <XCEngine/Core/Containers/Array.h>
#include <filesystem>

using namespace XCEngine::Resources;
using namespace XCEngine::Containers;

namespace {

std::string GetMeshFixturePath(const char* fileName) {
    return (std::filesystem::path(XCENGINE_TEST_FIXTURES_DIR) / "Resources" / "Mesh" / fileName).string();
}

TEST(MeshLoader, GetResourceType) {
    MeshLoader loader;
    EXPECT_EQ(loader.GetResourceType(), ResourceType::Mesh);
}

TEST(MeshLoader, GetSupportedExtensions) {
    MeshLoader loader;
    auto extensions = loader.GetSupportedExtensions();
    EXPECT_GE(extensions.Size(), 1u);
}

TEST(MeshLoader, CanLoad) {
    MeshLoader loader;
    EXPECT_TRUE(loader.CanLoad("test.obj"));
    EXPECT_TRUE(loader.CanLoad("test.fbx"));
    EXPECT_TRUE(loader.CanLoad("test.gltf"));
    EXPECT_TRUE(loader.CanLoad("test.OBJ"));
    EXPECT_FALSE(loader.CanLoad("test.txt"));
    EXPECT_FALSE(loader.CanLoad("test.png"));
}

TEST(MeshLoader, LoadInvalidPath) {
    MeshLoader loader;
    LoadResult result = loader.Load("invalid/path/mesh.obj");
    EXPECT_FALSE(result);
}

TEST(MeshLoader, LoadValidObjMesh) {
    MeshLoader loader;
    const std::string path = GetMeshFixturePath("triangle.obj");

    LoadResult result = loader.Load(path.c_str());
    ASSERT_TRUE(result);
    ASSERT_NE(result.resource, nullptr);

    auto* mesh = static_cast<Mesh*>(result.resource);
    EXPECT_EQ(mesh->GetVertexCount(), 3u);
    EXPECT_EQ(mesh->GetIndexCount(), 3u);
    EXPECT_EQ(mesh->GetVertexStride(), sizeof(StaticMeshVertex));
    EXPECT_FALSE(mesh->IsUse32BitIndex());
    ASSERT_EQ(mesh->GetSections().Size(), 1u);
    EXPECT_EQ(mesh->GetSections()[0].vertexCount, 3u);
    EXPECT_EQ(mesh->GetSections()[0].indexCount, 3u);
    EXPECT_TRUE(HasVertexAttribute(mesh->GetVertexAttributes(), VertexAttribute::Position));
    EXPECT_TRUE(HasVertexAttribute(mesh->GetVertexAttributes(), VertexAttribute::Normal));
    EXPECT_TRUE(HasVertexAttribute(mesh->GetVertexAttributes(), VertexAttribute::UV0));
    EXPECT_EQ(mesh->GetBounds().GetMin(), XCEngine::Math::Vector3(0.0f, 0.0f, -1.0f));
    EXPECT_EQ(mesh->GetBounds().GetMax(), XCEngine::Math::Vector3(1.0f, 1.0f, -1.0f));
    EXPECT_EQ(mesh->GetSections()[0].bounds.GetMin(), XCEngine::Math::Vector3(0.0f, 0.0f, -1.0f));
    EXPECT_EQ(mesh->GetSections()[0].bounds.GetMax(), XCEngine::Math::Vector3(1.0f, 1.0f, -1.0f));

    const auto* vertices = static_cast<const StaticMeshVertex*>(mesh->GetVertexData());
    ASSERT_NE(vertices, nullptr);
    EXPECT_FLOAT_EQ(vertices[0].position.x, 0.0f);
    EXPECT_FLOAT_EQ(vertices[0].position.y, 0.0f);
    EXPECT_FLOAT_EQ(vertices[0].position.z, -1.0f);
    EXPECT_FLOAT_EQ(vertices[0].normal.z, -1.0f);
    EXPECT_FLOAT_EQ(vertices[1].uv0.x, 1.0f);
    EXPECT_FLOAT_EQ(vertices[2].uv0.y, 1.0f);

    delete mesh;
}

TEST(MeshLoader, GeneratesNormalsAndTangentsWhenRequested) {
    MeshLoader loader;
    MeshImportSettings settings;
    settings.AddImportFlag(MeshImportFlags::GenerateNormals);
    settings.AddImportFlag(MeshImportFlags::GenerateTangents);

    const std::string path = GetMeshFixturePath("triangle_no_normals.obj");
    LoadResult result = loader.Load(path.c_str(), &settings);
    ASSERT_TRUE(result);
    ASSERT_NE(result.resource, nullptr);

    auto* mesh = static_cast<Mesh*>(result.resource);
    EXPECT_TRUE(HasVertexAttribute(mesh->GetVertexAttributes(), VertexAttribute::Normal));
    EXPECT_TRUE(HasVertexAttribute(mesh->GetVertexAttributes(), VertexAttribute::Tangent));
    EXPECT_TRUE(HasVertexAttribute(mesh->GetVertexAttributes(), VertexAttribute::Bitangent));

    const auto* vertices = static_cast<const StaticMeshVertex*>(mesh->GetVertexData());
    ASSERT_NE(vertices, nullptr);
    EXPECT_GT(vertices[0].normal.Magnitude(), 0.0f);
    EXPECT_GT(vertices[0].tangent.Magnitude(), 0.0f);
    EXPECT_GT(vertices[0].bitangent.Magnitude(), 0.0f);

    delete mesh;
}

} // namespace